Airbags are common, sometimes legally required, safety equipment when provided in motor vehicles and are designed to offer added protection to occupants in the event of an accident. A conventional vehicular airbag assembly typically includes a gas-inflatable bag, which is retained in its collapsed state (stowed) within a housing and inflates (rapidly) in response to a certain level of impact from a vehicle striking or being struck in one or more directions.
Large manufacturers of automobiles first provided airbags in the steering wheels of automobiles (driver-side airbags) as part of an airbag restraint system. Later, passenger-side airbags provided, for example, in the front dashboard or glove box became increasingly common. More recently, side-impact airbag assemblies (“SABs”) designed to protect the head and/or chest of an occupant in the event of an impact (e.g., accident) involving the side of the vehicle have been provided in various automobile models and continue to gain popularity.
According to the National Highway Traffic Safety Administration (“NHTSA”) of the United States Department of Transportation, there are three main types of SABs: chest (or torso) SABs, head SABs and head/chest combination SABs. Chest SABs are conventionally mounted in the side of a seat or in a door and are designed to offer protection to the chest of an adult occupant. Head SABs are conventionally mounted in the roof rail (within the headliner of a vehicle) above the side windows and are designed to offer protection to the head of an adult occupant. Moreover, there are two main types of head SABs: curtain SABs and tubular SABs. Typically, curtain SABs are designed to offer protection to both front and rear occupants during side impact and some designs provide a degree of protection from ejection if an automobile is involved in a roll-over event, while tubular SABs are typically designed to offer protection to front occupants. Lastly, head/chest combination SABs are conventionally mounted in the side of a seat and are often larger than chest SABs, and are designed to offer protection to both the head and chest of an adult occupant.
Unlike many frontal vehicular airbags (e.g., driver-side and passenger-side airbags), some SABs (e.g., curtain SABs) may not start to deflate for several seconds after inflation to offer added protection in the event of a roll-over. Importantly, many passenger vehicles can be equipped with both frontal and side-impact airbags, each airbag offering some additional protection. Likewise, additional airbag designs within or outside the above described categories are being considered and it would not be unexpected if new designs relying on like principles are incorporated into various passenger vehicles.
Airbag housings and/or covers often function to keep the stowed airbag in its folded state and to generally protect the airbag. Airbag covers (wraps) that are made from fabric or thin, pliable plastics are particularly useful in mounting side curtain airbags where more rigid housings can be difficult to effectively use due to the limited space offered by recesses often used for mounting the airbags around the openings defining passenger doors and/or windows.
Important properties of any housing or cover for a vehicular airbag include that the housings or covers should be forced open reliably and nearly instantaneously upon deployment of the airbag, which, for example, can happen within a fraction of a second (e.g., within milliseconds for some airbag assemblies including some SABS) after some predetermined level of impact. It is also usually desirable that the airbag housing opens at a predetermined portion(s) in order to assist in properly deploying the airbag in a desired orientation. Known airbag housings often have a frangible feature such as a line/region of mechanical weakness (e.g., a perforation) that fails when some amount of force is applied.
Unfortunately, tubular covers (wraps) having perforated regions of weakness require that certain considerations are undertaken such as whether the perforated area will stay intact during fabrication, shipping and installation while still having sufficient tearing properties for responding to airbag deployment. Particularly, such wraps relying on perforated regions require that the cover be applied in a tubular configuration to the airbag, which requires a certain level of delicacy and a certain amount of time in order to avoid premature tearing and to achieve proper placement. Such considerations have economic consequences.